l.c.v._.BranchFileSystemClient : class documentation

Instances of this class wrap the methods of the codehosting endpoint
required by the VFS code, specialized for a particular user.

The wrapper also caches the results of calls to translatePath in order to
avoid a large number of roundtrips. In the normal course of operation, our
Bazaar transport translates virtual paths to real paths on disk using this
client. It does this many, many times for a single Bazaar operation, so we
cache the results here.